Molecular basis for control of antibiotic production by a bacterial hormone.

Actinobacteria produce numerous antibiotics and other specialized metabolites that have important applications in medicine and agriculture1. Diffusible hormones frequently control the production of such metabolites by binding TetR family transcriptional repressors (TFTRs), but the molecular basis for this remains unclear2. The production of methylenomycin antibiotics in Streptomyces coelicolor A3(2) is initiated by the binding of 2-alkyl-4-hydroxymethylfuran-3-carboxylic acid (AHFCA) hormones to the TFTR MmfR3. Here we report the X-ray crystal structure of an MmfR-AHFCA complex, establishing the structural basis for hormone recognition. We also elucidate the mechanism for DNA release upon hormone binding through the single-particle cryo-electron microscopy structure of an MmfR-operator complex. DNA binding and release assays with MmfR mutants and synthetic AHFCA analogues define the role of individual amino acid residues and hormone functional groups in ligand recognition and DNA release. These findings will facilitate the exploitation of actinobacterial hormones and their associated TFTRs in synthetic biology and in the discovery of new antibiotics.

A single sensor controls large variations in zinc quotas in a marine cyanobacterium.

Marine cyanobacteria are critical players in global nutrient cycles that crucially depend on trace metals in metalloenzymes, including zinc for CO2 fixation and phosphorus acquisition. How strains proliferating in the vast oligotrophic ocean gyres thrive at ultra-low zinc concentrations is currently unknown. Using Synechococcus sp. WH8102 as a model we show that its zinc-sensor protein Zur differs from all other known bacterial Zur proteins in overall structure and the location of its sensory zinc site. Uniquely, Synechococcus Zur activates metallothionein gene expression, which supports cellular zinc quotas spanning two orders of magnitude. Thus, a single zinc sensor facilitates growth across pico- to micromolar zinc concentrations with the bonus of banking this precious resource. The resultant ability to grow well at both ultra-low and excess zinc, together with overall lower zinc requirements, likely contribute to the broad ecological distribution of Synechococcus across the global oceans.

EMACO for treatment of gestational trophoblastic neoplasia: A multinational multicenter study.

OBJECTIVE: To investigate the efficacy and toxicity of etoposide, methotrexate, actinomycin D alternating with cyclophosphamide, and vincristine (EMACO) for treatment of gestational trophoblastic neoplasia, and for factors independently associated with EMACO resistance and disease-specific death in an international cohort. METHODS: Medical records of GTN patients who received EMACO during 1986-2019 from gestational trophoblastic disease centers from four countries including the USA, Thailand, Hungary, and Brazil, were retrospectively reviewed. Among 335 GTN patients, 266 patients who received EMACO as primary chemotherapy were included in the primary treatment group, and 69 patients who received EMACO after relapse/resistance to single-agent chemotherapy were included in the prior treatment group. RESULTS: Three-quarters (76.1%) of all patients achieved remission, and the survival rate was 89%. The prior treatment group had better outcomes than the primary treatment group relative to remission rate (87.0% vs. 73.3%, p = 0.014) and number of EMACO cycles to achieve remission (3 vs. 6 cycles, p < 0.001). Sustained remission increased to 87.2% in EMACO-resistant patients treated with later-line chemotherapy. Number of metastatic organs ≥2 (adjusted odds ratio [aOR]: 2.33, p = 0.049) was the only independent predictor of EMACO resistance among overall patients. Interval from index pregnancy ≥7 months (aOR: 4.34, p = 0.001), and pretreatment hCG >100,000 IU/L (aOR: 2.85, p = 0.028) were independent predictors of EMACO resistance in the high-risk subgroup. The only factor independently associated with disease-specific death was EMACO resistance (aOR: 176.04, p < 0.001). CONCLUSIONS: EMACO is an effective treatment for GTN. Number of metastatic organs and EMACO resistance were the independent predictors of EMACO resistance and disease-specific death, respectively.

Extracellular alpha/beta-hydrolase from Paenibacillus species shares structural and functional homology to tobacco salicylic acid binding protein 2.

An alpha/ beta hydrolase annotated as a putative salicylate esterase within the genome of a species of Paenibacillus previously identified from differential and selective growth on Kraft lignin was structurally and functionally characterised. Feruloyl esterases are key to the degradation of lignin in several bacterial species and although this activity was investigated, no such activity was observed. The crystal structure of the Paenibacillus esterase, here denoted as PnbE, was determined at 1.32 Å resolution, showing high similarity to Nicotiana tabacum salicylic acid binding protein 2 from the protein database. Structural similarities between these two structures across the core domains and key catalytic residues were observed, with superposition of catalytic residues giving an RMSD of 0.5 Å across equivalent Cα atoms. Conversely, the cap domains of PnbE and Nicotiana tabacum SABP2 showed greater divergence with decreased flexibility in the PnbE cap structure. Activity of PnbE as a putative methyl salicylate esterase was supported with binding studies showing affinity for salicylic acid and functional studies showing methyl salicylate esterase activity. We hypothesise that this activity could enrich Paenibacillus sp. within the rhizosphere by increasing salicylic acid concentrations within the soil.

Characterization of Thiamine Diphosphate-Dependent 4-Hydroxybenzoylformate Decarboxylase Enzymes from Rhodococcus jostii RHA1 and Pseudomonas fluorescens Pf-5 Involved in Degradation of Aryl C2 Lignin Degradation Fragments.

A thiamine diphosphate-dependent enzyme annotated as a benzoylformate decarboxylase is encoded by gene cluster ro02984-ro02986 in Rhodococcus jostii RHA1 previously shown to generate vanillin and 4-hydroxybenzaldehyde from lignin oxidation, and a closely related gene cluster is also found in the genome of Pseudomonas fluorescens Pf-5. Two hypotheses for possible pathways involving a thiamine diphosphate-dependent cleavage, either C-C cleavage of a ketol or diketone aryl C3 substrate or decarboxylation of an aryl C2 substrate, were investigated by expression and purification of the recombinant enzymes and expression of dehydrogenase and oxidase enzymes also found in the gene clusters. The ThDP-dependent enzymes showed no activity for cleavage of aryl C3 ketol or diketone substrates but showed activity for decarboxylation of benzoylformate and 4-hydroxybenzoylformate. A flavin-dependent oxidase encoded by gene ro02984 was found to oxidize either mandelic acid or phenylglyoxal. The crystal structure of the P. fluorescens decarboxylase enzyme was determined at 1.69 Å resolution, showing similarity to structures of known benzoylformate decarboxylase enzymes. The P. fluorescens decarboxylase enzyme showed enhanced carboligase activity between vanillin and acetaldehyde, rationalized by the presence of alanine versus serine at residue 73 in the enzyme active site, which was investigated further by site-directed mutagenesis of this residue. A hypothesis for a pathway for degradation of aryl C2 fragments arising from oxidative cleavage of phenylcoumaran and diarylpropane structures in lignin is proposed.

Binding of Distinct Substrate Conformations Enables Hydroxylation of Remote Sites in Thaxtomin D by Cytochrome P450 TxtC.

Cytochromes P450 (CYPs) catalyze various oxidative transformations in drug metabolism, xenobiotic degradation, and natural product biosynthesis. Here we report biochemical, structural, and theoretical studies of TxtC, an unusual bifunctional CYP involved in the biosynthesis of the EPA-approved herbicide thaxtomin A. TxtC was shown to hydroxylate two remote sites within the Phe residue of its diketopiperazine substrate thaxtomin D. The reactions follow a preferred order, with hydroxylation of the α-carbon preceding functionalization of the phenyl group. To illuminate the molecular basis for remote site functionalization, X-ray crystal structures of TxtC in complex with the substrate and monohydroxylated intermediate were determined. Electron density corresponding to a diatomic molecule (probably dioxygen) was sandwiched between the heme iron atom and Thr237 in the TxtC-intermediate structure, providing insight into the mechanism for conversion of the ferrous-dioxygen complex into the reactive ferryl intermediate. The substrate and monohydroxylated intermediate adopted similar conformations in the active site, with the π-face of the phenyl group positioned over the heme iron atom. Docking simulations reproduced this observation and identified a second, energetically similar but conformationally distinct binding mode in which the α-hydrogen of the Phe residue is positioned over the heme prosthetic group. Molecular dynamics simulations confirmed that the α-hydrogen is sufficiently close to the ferryl oxygen atom to be extracted by it and indicated that the two substrate conformations cannot readily interconvert in the active site. These results indicate that TxtC is able to hydroxylate two spatially remote sites by binding distinct conformations of the substrate and monohydroxylated intermediate.

Structure of Thermobifida fusca DyP-type peroxidase and activity towards Kraft lignin and lignin model compounds.

A Dyp-type peroxidase enzyme from thermophilic cellulose degrader Thermobifida fusca (TfuDyP) was investigated for catalytic ability towards lignin oxidation. TfuDyP was characterised kinetically against a range of phenolic substrates, and a compound I reaction intermediate was observed via pre-steady state kinetic analysis at λmax 404 nm. TfuDyP showed reactivity towards Kraft lignin, and was found to oxidise a ß-aryl ether lignin model compound, forming an oxidised dimer. A crystal structure of TfuDyP was determined, to 1.8 Å resolution, which was found to contain a diatomic oxygen ligand bound to the heme centre, positioned close to active site residues Asp-203 and Arg-315. The structure contains two channels providing access to the heme cofactor for organic substrates and hydrogen peroxide. Site-directed mutant D203A showed no activity towards phenolic substrates, but reduced activity towards ABTS, while mutant R315Q showed no activity towards phenolic substrates, nor ABTS.

Breech presentation: its predictors and consequences. An analysis of the Hungarian Tauffer Obstetric Database (1996-2011).

INTRODUCTION: Breech presentation is linked to abnormal pregnancy outcomes. However, the causality of this association is unknown. We aimed to investigate predictors of term breech presentation and pregnancy outcomes of breech presentation. MATERIAL AND METHODS: Using a Hungarian registry, all term (≥ 37 weeks), singleton pregnancies with cephalic, and breech presentation in 1996-2011 were analyzed (n = 41 796). Covariates were maternal medical history and data on the present pregnancy. Multivariable logistic regression was used to investigate predictors of breech presentation and of delivery (cesarean section or other obstetrical interventions at birth) and fetal outcomes (Apgar score ≤ 7, need for perinatal intensive treatment, intrauterine death or perinatal mortality) related to breech presentation. RESULTS: Breech presentation was independently associated with older maternal age, medical history (primiparity, stillbirth, spontaneous abortion, hormone treatment, and assisted reproduction), maternal morbidities (hypertension and oligohydramnios), and the fetal factors (female sex, younger gestational age at delivery, developmental abnormalities, small for gestational age, and birthweight). An adverse delivery outcome was 11.7 times (95% confidence interval 11.3-12.0) and an adverse fetal outcome was 1.39 times (95% confidence interval 1.33-1.45) more frequent in pregnancies with breech presentation compared with cephalic presentation. Further adjustment for predictors of breech presentation had no major effect on the delivery outcome, but it reduced the risk of adverse fetal outcome (odds ratio 1.18, 95% confidence interval 1.14-1.24). CONCLUSIONS: Breech presentation is a marker of pathological pregnancy and is independently associated with an increased risk of gestational complications. Closer surveillance and appropriate management of pregnancies with breech presentation is warranted to prevent adverse perinatal outcomes.

The Role of Surgery in the Management of Gestational Trophoblastic Neoplasia The Hungarian Experience.

OBJECTIVE: To review the role of surgery in the management of gestational trophoblastic neoplasia (GTN) over the past 38 years in our national trophoblastic disease center. STUDY DESIGN: Between January 1, 1977, and December 31, 2014, 371 patients with low-risk GTN and 190 patients with high-risk GTN were treated with chemotherapy, surgical interventions, or both. The indications for hysterectomy included excision of large uterine tumor masses, uterine hemorrhage or sepsis, or a drug-resistant uterine focus. Metastases were excised due to the presence of drug-resistant foci or complications of disease such as hemorrhage. RESULTS: Over the period of 1977-2014 74 hysterectomies, 15 resections of vaginal metastases, 3 omentectomies, 13 adnexectomies, 9 lung resections, I nephrectomy, 1 lung resection and nephrectomy, and 2 craniotomies were performed among our patients. While hysterectomy was performed in 51 (26.8%) of 190 high-risk patients, hysterectomy was performed in only 23 (6.2%) of 371 low-risk patients (p < 0.01). From 1977-2006 metastases were resected in 18.3% (26/142) and from 2007-2014 in 16.7% (8/48) of high-risk patients. CONCLUSION: In our center surgery, particularly in the form of hysterectomy, still plays a valuable role in the management of both low- and high-risk GTN.

Specificity determinants for lysine incorporation in Staphylococcus aureus peptidoglycan as revealed by the structure of a MurE enzyme ternary complex.

Formation of the peptidoglycan stem pentapeptide requires the insertion of both L and D amino acids by the ATP-dependent ligase enzymes MurC, -D, -E, and -F. The stereochemical control of the third position amino acid in the pentapeptide is crucial to maintain the fidelity of later biosynthetic steps contributing to cell morphology, antibiotic resistance, and pathogenesis. Here we determined the x-ray crystal structure of Staphylococcus aureus MurE UDP-N-acetylmuramoyl-L-alanyl-D-glutamate:meso-2,6-diaminopimelate ligase (MurE) (E.C. 6.3.2.7) at 1.8 Šresolution in the presence of ADP and the reaction product, UDP-MurNAc-L-Ala-γ-D-Glu-L-Lys. This structure provides for the first time a molecular understanding of how this Gram-positive enzyme discriminates between L-lysine and D,L-diaminopimelic acid, the predominant amino acid that replaces L-lysine in Gram-negative peptidoglycan. Despite the presence of a consensus sequence previously implicated in the selection of the third position residue in the stem pentapeptide in S. aureus MurE, the structure shows that only part of this sequence is involved in the selection of L-lysine. Instead, other parts of the protein contribute substrate-selecting residues, resulting in a lysine-binding pocket based on charge characteristics. Despite the absolute specificity for L-lysine, S. aureus MurE binds this substrate relatively poorly. In vivo analysis and metabolomic data reveal that this is compensated for by high cytoplasmic L-lysine concentrations. Therefore, both metabolic and structural constraints maintain the structural integrity of the staphylococcal peptidoglycan. This study provides a novel focus for S. aureus-directed antimicrobials based on dual targeting of essential amino acid biogenesis and its linkage to cell wall assembly.

The loops facing the active site of prolyl oligopeptidase are crucial components in substrate gating and specificity.

Prolyl oligopeptidase (POP) has emerged as a drug target for neurological diseases. A flexible loop structure comprising loop A (res. 189-209) and loop B (res. 577-608) at the domain interface is implicated in substrate entry to the active site. Here we determined kinetic and structural properties of POP with mutations in loop A, loop B, and in two additional flexible loops (the catalytic His loop, propeller Asp/Glu loop). POP lacking loop A proved to be an inefficient enzyme, as did POP with a mutation in loop B (T590C). Both variants displayed an altered substrate preference profile, with reduced ligand binding capacity. Conversely, the T202C mutation increased the flexibility of loop A, enhancing the catalytic efficiency beyond that of the native enzyme. The T590C mutation in loop B increased the preference for shorter peptides, indicating a role in substrate gating. Loop A and the His loop are disordered in the H680A mutant crystal structure, as seen in previous bacterial POP structures, implying coordinated structural dynamics of these loops. Unlike native POP, variants with a malfunctioning loop A were not inhibited by a 17-mer peptide that may bind non-productively to an exosite involving loop A. Biophysical studies suggest a predominantly closed resting state for POP with higher flexibility at the physiological temperature. The flexible loop A, loop B and His loop system at the active site is the main regulator of substrate gating and specificity and represents a new inhibitor target.

Evolution of substrate specificity in a recipient's enzyme following horizontal gene transfer.

Despite the prominent role of horizontal gene transfer (HGT) in shaping bacterial metabolism, little is known about the impact of HGT on the evolution of enzyme function. Specifically, what is the influence of a recently acquired gene on the function of an existing gene? For example, certain members of the genus Corynebacterium have horizontally acquired a whole l-tryptophan biosynthetic operon, whereas in certain closely related actinobacteria, for example, Mycobacterium, the trpF gene is missing. In Mycobacterium, the function of the trpF gene is performed by a dual-substrate (ßα)8 phosphoribosyl isomerase (priA gene) also involved in l-histidine (hisA gene) biosynthesis. We investigated the effect of a HGT-acquired TrpF enzyme upon PriA's substrate specificity in Corynebacterium through comparative genomics and phylogenetic reconstructions. After comprehensive in vivo and enzyme kinetic analyses of selected PriA homologs, a novel (ßα)8 isomerase subfamily with a specialized function in l-histidine biosynthesis, termed subHisA, was confirmed. X-ray crystallography was used to reveal active-site mutations in subHisA important for narrowing of substrate specificity, which when mutated to the naturally occurring amino acid in PriA led to gain of function. Moreover, in silico molecular dynamic analyses demonstrated that the narrowing of substrate specificity of subHisA is concomitant with loss of ancestral protein conformational states. Our results show the importance of HGT in shaping enzyme evolution and metabolism.

Changes in the management of high-risk gestational trophoblastic neoplasia in the National Trophoblastic Disease Center of Hungary.

OBJECTIVE: To compare the clinical management of patients with high-risk gestational trophoblastic neoplasia (GTN) among the periods of 1977-1990, 1991-2000, and 2001-2012 at the National Trophoblastic Disease Center of Hungary and to assess the efficacy of the FIGO 2000 staging and risk factor scoring system in comparison to the original WHO prognostic scoring system (1983). STUDY DESIGN: We reviewed the medical records of 185 patients with high-risk GTN. From 1977-2000, patients were classified according to the original WHO prognostic scoring system (1983). From 2001-2012, high-risk patients were categorized by the FIGO 2000 system. We assessed the efficacy of MAC and EMA-CO primary combination chemotherapies. For 1977-2006 and 2007-2012 we assessed the efficacy of MAC and EMA-CO primary combination chemotherapies. RESULTS: From 1977-1990, 63 high-risk patients (average, 4-5 patients/year), from 1991-2000, 50 high-risk patients (average, 5 patients/year), and from 2001-2012, 72 high-risk patients (average, 6 patients/year) were treated primarily with combination chemotherapy (MAC and/or EMA-CO and/or CEB). From 1977-2006, 100 high-risk patients received MAC primary combination chemotherapy and 17 cases received EMA-CO. The ratio of primary MAC primarily with and EMA-CO therapy among our high-risk patients was 5.9 (100/17) over the referred period. From 2007-2012, 21 high-risk patients were treated with primary MAC chemotherapy and 16 patients received EMA-CO. The MAC/EMA-CO ratio over this time interval was 1.3 (21/16). CONCLUSION: We attained complete remission in 95.7% of the high-risk patients. During the last 6 years the use of EMA-CO primary combination chemotherapy increased among our high-risk patients, which has resulted in increased efficacy and fewer side effects.

Study of the Conformational Dynamics of Prolyl Oligopeptidase by Mass Spectrometry: Lessons Learned.

Ion mobility mass spectrometry (IM-MS) can be used to analyze native proteins according to their size and shape. By sampling individual molecules, it allows us to study mixtures of conformations, as long as they have different collision cross sections and maintain their native conformation after dehydration and vaporization in the mass spectrometer. Even though conformational heterogeneity of prolyl oligopeptidase has been demonstrated in solution, it is not detectable in IM-MS. Factors that affect the conformation in solution, binding of an active site ligand, the stabilizing Ser554Ala mutation, and acidification do not qualitatively affect the collision-induced unfolding pattern. However, measuring the protection of accessible cysteines upon ligand binding provides a principle for the development of MS-based ligand screening methods.

Clinical epidemiology and management of gestational trophoblastic neoplasia in Hungary in the past 34 years.

OBJECTIVE: To review our clinical experience in the treatment of patients with gestational trophoblastic neoplasia (GTN) over the past 34 years in our national trophoblastic disease center. STUDY DESIGN: Between January 1, 1977, and December 31, 2010, 331 patients with low-risk GTN and 174 patients with high-risk GTN (altogether 505) were treated. The patients were directed to the national trophoblastic disease center from all parts of Hungary. The patients were between 14 and 54 years of age, with an average age of 28.7 years. Primary chemotherapy was selected based upon the patient's stage and prognostic score of GTN. RESULTS: Among 237 low-risk patients, 228 (96.2%) achieved remission as a result of primary methotrexate (MTX) therapy. Out of 94 low-risk patients 90 (95.7%) achieved remission as a result of primary actinomycin-D (Act-D) therapy. MTX, Act-D and cyclophosphamide (MAC) as a primary therapy was used in 118 high-risk cases, and 110 (93.2%) patients achieved complete remission. A total of 32 high-risk patients were treated with the etoposide, high-dose MTX/folinic acid, Act-D, cyclophosphamide and vincristine (EMA-CO) regimen, and of 26 primary therapies complete remission was achieved in 21 (80.8%) cases. Primary cisplatin, etoposide and bleomycin (CEB) therapy was successful in 16 of 17 high-risk cases (94.1%). Metastases were found in 47.3% (239/505) of the patients. Hysterectomy was performed in 68 of 505 (13.5%) cases. Chemotherapy, surgical intervention or other supplementary treatments resulted in 100% remission in cases of nonmetastatic and metastatic low-risk disease. Comparison of mean prognostic scores resulted in significant differences between CEB and MAC, CEB and EMA-CO, and MAC and EMA-CO. CONCLUSION: Our data indicate that MTX/folinic acid or Act-D should be the primary treatment in patients with nonmetastatic or metastatic low-risk GTN. Patients with high-risk metastatic GTN should be treated primarily with combination chemotherapy. Our data support the effectiveness of MAC, EMA-CO and CEB regimens. Results also show that patient care under the direction of experienced clinicians serves to optimize the opportunity for cure and minimize morbidity.

Vascular endothelial growth factors and their receptors and regulators in gestational trophoblastic diseases and normal placenta.

OBJECTIVE: To study the expression of vascular endothelial growth factors (VEGFs), placental growth factor (PLGF) and their receptors (VEGFR-1, -2, -3) and their regulators (IL-6, CD147) in normal placenta and gestational trophoblastic disease (GTD) in order to evaluate their potential role in the biology of GTD. STUDY DESIGN: Paraffin sections of 10 normal, first-trimester placentas, 10 partial moles, 10 complete moles, 5 choriocarcinomas and 5 placental site trophoblastic tumors (PSTTs) were studied immunohistochemically for expression of VEGFR-1, VEGFR-2, VEGFR-3, IL-6, PLGF and CD147. Immunolocalization of VEGF, Angiopoietin-1 and Angiopoietin-2 was performed on 5 choriocarcinomas and 5 PSTTs. The levels of VEGF and VEGFR-2 were determined in supernatants and lysates of normal trophoblast, JEG-3 and JAR choriocarcinoma cells with electrochemiluminescence assays. RESULTS: The normal placenta had significantly stronger expression of VEGFR-2 than did those of partial and complete mole (p = 0.001, p = 0.003). VEGF, Angiopoietin-1 and Angiopoietin-2 expression in PSTT were significantly higher than those in choriocarcinoma (p = 0.002, p= 0.01, p = 0.038). Choriocarcinoma showed stronger intensity of staining for VEGFR-3 than did normal placenta, partial and complete mole (p = 0.036, p = 0.038, p = 0.05). Choriocarcinoma had significantly stronger staining of CD147 than did partial and complete mole (p<0.01, p<0.01). PSTT exhibited significantly stronger staining for IL-6 than did choriocarcinoma (p = 0.03). CONCLUSION: PSTTs exhibited strong staining for VEGF, and choriocarcinoma showed strong staining for VEGFR-3. Agents that inhibit the activity of VEGF and VEGF receptors may prove to be useful in the therapy of gestational trophoblastic neoplasia.

Clinical aspects of decidualization / A decidualizáció klinikai vonatkozásai

An essential component of successful conception and pregnancy is decidualization, which involves structural and functional transformation of the endometrium. The process involves structural changes in the uterine mucosa, transformation of spiral arterioles, numerical and functional adaptation of leukocytes in the endometrium and their subsequent migration, and functional and morphological changes in decidual stromal cells. As part of decidualization, trophoblast cells of embryonic origin perform a physiological invasion of maternal tissue to create the placenta. The success of the process is due to the special antigenicity of the trophoblast cells and the immune communication between the graft (fetus) and the host (mother) through hormones, cytokines and multiple receptorligand connections. Disorders of these processes are the basis of several diseases that threaten conception, implantation, and successful pregnancy, such as recurrent miscarriage, preeclampsia, intrauterine retardation, or preterm birth. In this article, we review the anatomical, immunological, and molecular basis of physiological decidualization to address common disorders in the clinical practice of obstetrics that are related to a dysfunctional decidualization.

The role of natural killer cells in the immune homeostasis of the maternal fetal interface / A természetes ölosejtek szerepe az anyai-magzati immunhomeostasis fenntartásában

Successful conception, implantation and pregnancy require a complex and organized communication between the embryonal (allograft) and the maternal (host) immune system. Different leukocyte subsets have an important role in orchestrating the immune response at the fetal-maternal interface. There are certain similarities between the immune invasion of tumor cells and the physiological invasion of the trophoblastic cells of embryonic origin into the maternal decidua. The decidual natural killer cells are a special subset of natural killer cells and alongside with macrophages and dendritic cells, they are part of the innate immune system therefore they are the first immune cells contacting any intruder whether it is a tumor or embryonic tissue. Interestingly decidual natural killer cells not only do not eliminate invasive trophoblastic cells, but specifically promote their progression. Their angiogenic activity facilitates and coordinates local vascular remodeling of the forming placenta. In this article we review the different nature of trophoblastic cell and decidual natural killer cell interaction, the role of decidual natural killer cells in the vascularization and immune homeostasis of the decidua.

Isolation and culture of decidual natural killer cells from term placenta and complete hydatidiform mole.

Decidual natural killer cells (dNK) have been the focus of many studies because of their unique roles in both the anti-tumor immune response and healthy placental formation. Revealing the immunological mechanisms by which they interact with their target cells may lead to a better understanding of immune evasion of certain tumor cells, including abnormal cells of the different forms of gestational trophoblast disease and miscarriages of immunologic origin. Efforts to perform functional immunological studies on dNK cells have been limited by difficulty obtaining sufficent quantities of cells and sustaining the dNK phenotype. A novel protocol was developed to isolate and culture dNK cells from fresh, term placentas and complete hydatidiform moles.The placental samples were collected from healthy women undergoing scheduled elective cesarean delivery. The molar samples were collected after evacuation and curettage. Tissue samples were made into single cell suspensions using mechanical and enzymatic degradation, followed by fluorescence-activated cell sorting (FACS) using surface markers. The dNK cells were then expanded in cell culture. Their surface markers and cytotoxicity were reassessed by flow cytometry and functional assays. The protocol produces high quantities of enriched dNK cells which can be sustained in cell culture for at least a month, preserving their phenotype and funcionality for a week.

Application of a novel microscopic technique for quantifying CA125 binding to circulating mononuclear cells in longitudinal specimens during treatment for ovarian cancer.

BACKGROUND: Measurement of serum CA125, an antigenic fragment of human mucin 16 (MUC16), is used to monitor the clinical progression of epithelial ovarian cancer (EOC). However, rather than simply a passive marker reflecting tumor burden, MUC16 may have a more active role by binding to immune cells and altering their tumor response. We developed a research tool to measure MUC16-binding to the surfaces of peripheral blood mononuclear cell (PBMC) subtypes and tested its research value using specimens collected serially from a woman being treated for high grade serous EOC. METHODS: Cryopreserved PBMCs were mixed with anti-CA125 antibody-labeled plasmonic gold nanoparticles (PNPs) to detect cell surface MUC16-binding along with fluorescent stains to identify B cells, NK cells, NK-T cells, T cells, and monocytes. From 3D darkfield images, a computer algorithm was applied to enumerate PNP-binding and fluorescence microscopy to identify cell lineage. Average MUC16-binding was determined by fitting a Poisson distribution to PNP-counts across similar cell types. MUC16-binding to cell types was correlated with treatment details, CA125 levels, and complete blood count (CBC) data. RESULTS: Over a 21-month period, monocytes had the highest level of MUC16-binding which was positively correlated with serum CA125 and inversely correlated with circulating monocyte and lymphocyte counts. Fluctuations of PNP-binding to NK cells were associated temporally with types of chemotherapy and surgical events. Levels of MUC16 bound to NK cells were positively correlated with levels of MUC16 bound to T and NK-T cells and inversely correlated with circulating platelets. CONCLUSIONS: Assessment of MUC16-binding among cryopreserved PBMC cell types can be accomplished using darkfield and fluorescence microscopy. Correlations observed between level of binding by cell type with serum CA125, CBC data, and treatment details suggest that the new techniques may offer novel insights into EOC's clinical course.